Adding fully retractable seats would delay the reopening of the stadium for at least a year to the start of the 2015-16 football season, and require the injection of tens of millions of pounds in additional public funds, but Johnson is understood to believe it is the most viable long-term solution.

The plans were among a number of options discussed yesterday by the board of the London Legacy Development Corporation, chaired by Johnson. No final decision over the stadium’s future was taken but it was agreed the plans be developed further ahead of the next board meeting in December.

Should the target date of 2015 be hit it would allow the stadium to also host matches in that year’s Rugby World Cup.

Support for fully retractable seating represents a significant change in thinking at the LLDC, which has been grappling with how to provide a suitable environment for football while retaining the running track.

Retractable seating was rejected in the early planning stages of the £500 million stadium on the grounds of cost, and the fact that it is being discussed now highlights the flaws in the original plans.

Until recently the LLDC had been focused on discussing temporary seating options with West Ham, the likeliest long-term tenant. Temporary seats are now considered only a short-term solution, and there is an emerging consensus at City Hall to opt for fully retractable seats, or reject football altogether and accept that the stadium may require subsidies in future.

Last week LLDC acting chief executive Dennis Hone confirmed that long-term viability was the new priority. “Yes, the stadium is tricky. But it’s tricky because we want to get it right. I would hate to bung someone in there and see it fall apart in five years,” he said.

Discussions between West Ham and the LLDC have focused on temporary or ‘demountable’ seats built on the track behind the goals, but there are strong arguments against the plan.

Erecting and dismounting the temporary stands would take at least two weeks at the beginning and end of each season, taking the stadium out of use for a month each summer, when it should be used for athletics and concerts.

Construction and storage costs for the stands are estimated at £500,000 a year. Rather than taking three weeks to erect, retractable seats such as those in use at the Stade de France in Paris can be in place in a matter of hours at the touch of a button. But there are major risks attached to the plan, not least that no one has previously tried to retrofit such a system.

The plan would require the lower tier of the stadium to be demolished completely, and the new movable structure to be built from scratch. The upper tiers would remain in place.

A new roof would also be built to cover all the seats, though this would be likely to see the removal of the distinctive triangular floodlights, which are instantly recognisable but weigh 600 tonnes.

Discussions about how to pay for the work, which is estimated to cost £160 million-£200 million, are ongoing. The LLDC would like West Ham to contribute to the capital costs, but as tenants they have argued that the landlord should pay to provide an appropriate facility.

Newham Council has already agreed to commit £40 million to the LLDC for a stake in the stadium, and there is an existing budget of £95 million.

The mayor is considering a range of funding options, including borrowing at favourable rates, or lobbying for a share of the unspent Olympic contingency of more than £500 million to be allocated to the stadium.

The board also received an update on the legal position of a new European Commission inquiry into state aid in football. West Ham’s initial bid for the stadium collapsed because of a specific complaint to the EC.

This most recent case is a general inquiry from the EC competition commissioner into the relationship between football and public funding, and both LLDC and mayoral sources say they do not consider it a deal-breaker.